Apparatus for severing a length from a strip of rubber tire tread

Abstract

A circular rotatably driven knife assembly for cutting strips including a carriage for supporting the cutting knife and drive means for the carriage and knife. The knife structure has particular utility for cutting strips of vulcanized rubber such as the tread material adapted to be bonded to the outside of a tire casing, the knife having abrasive grits bonded to its side walls adjacent its periphery to buff the ends of the strip simultaneously with the cutting operation to condition the ends cut off of the portion of the strip for splicing during the vulcanizing step after the severed end of the strip has been wrapped around the tire with the ends pressed into contact with each other.

I claim: 
     
       1. Apparatus for severing a length from a strip of cured rubber tire tread comprising: a vertically disposed circular knife blade having an annular buffing zone containing abrasive grit extending inwardly from the peripheral cutting edge toward the center of the blade and projecting axially beyond the cutting edge for buffing a cut end of the strip simultaneously with the cutting of the strip; carriage means for rotatably supporting said blade, said carriage including vertical side walls parallel to and axially spaced from said blade, an axle for said blade mounted in said side walls near the lower edge thereof so that the cutting edge of said blade projects below said side walls; a frame for supporting said carriage for reciprocal movement along a horizontal path, said frame including horizontally spaced-apart stationary frame members extending along said path, said members being slidably engaged by the side walls of said carriage, said members defining a horizontal slot on each side of said carriage, and bearing means carried by said carriage side walls and riding in said slots; means for reciprocating said carriage along said horizontal path; and means for rotating said circular blade during horizontal movement of said carriage, said means including a sprocket wheel coaxial with and fixed to said blade, a pair of idler sprockets rotatably mounted on axles extending between the side walls of said carriage at locations fore and aft of said blade with respect to said horizontal path, and a stationary run of sprocket chain supported at its opposite ends by said frame, said chain extending between said carriage side walls and being threaded between said sprocket wheel and each of said idler sprockets. 
     
     
       2. Apparatus for cutting off from a strip of cured rubber tread strip a length of predetermined longitudinal dimension for use in retreading a tire and for simultaneously roughening the freshly cut end of both the strip and the length, said apparatus comprising: a carriage mounted in a stationary frame for reciprocating movement back and forth along a path across the longitudinal dimension of the tread strip; means for reciprocating said carriage along said path; a disc-like circular cutting blade mounted for rotation about its axis and supported by said carrier for movement therewith, said blade having side walls which converge at the periphery of the blade thereby forming a circular knife edge, each side wall having an annular zone containing abrasive grit extending from the circular knife edge toward the center and projecting axially beyond the knife edge; and means for rotating said blade at a peripheral speed which is higher than the speed at which said blade is moved along said path whereby said annular grit-containing zones roughen the ends of the strip and the length as the latter is severed from the strip.